Of iVHINSfONE and LAVA. 81 



it became gelatinous ; and being evaporated to drynefs, and di- 

 luted again with water, i grain of filex was left. The remain- 

 ing folution produced, to the laft drop, cryflals of alum*. 1 

 diilblved thefe cryflals in water, and precipitated the argil 

 by carbonate of ammonia. After being carefully warned, 

 dried, and heated red hot a quarter of an hour, it weighed 1 2 

 grains. 



8. The brownifh matter, No. 6. infoluble in cauftic potafh, 

 feemed to be oxyd of iron ', and after having been heated red hot, 

 weighed 24^ grains. I powdered this mafs, and poured on it 

 fome acetous acid, in order to detect magnelia; but nothing was 

 diffolved. It was next treated with nitric acid, which dhTolved 

 the iron, but left 4 grains of filex. The iron being precipitated, 

 dried, and heated red hot, weighed 20 grains, and was magne- 

 tic. Sufpecting that fome argil might ftill be mixed with it, 

 from having efcaped the action of the cauftic potafh, I diffolved 

 5 grains in muriatic acid, and precipitated the iron by PrufTian 

 alkali. Having feparated the blue precipitate, I boiled the folu- 

 tion with carbonate of foda, and obtained 1 grain of argil. 

 Thefe 20 grains confifted, therefore, of 16 grains of iron, and 4 

 grains of argil. 



The remaining part of the iron was melted for an hour, with 

 ten times its weight of nitre, in order to detect manganefe. The 

 mixture, however, when cold, was not greenifh ; and water 

 made a colourlefs folution of the faline matter, which did not 

 become turbid, when expofed fome days to the action of the 

 air "(% 



Part I. L 9. The 



* It therefore contained none of the "earth which Vauquelin lately difcovered, 

 and to which he has given the name of glucine. 



1 1 think, however, it is probable, that this bafalt contained a fmall quantity of 

 ■manganefe, both from the brownifh colour of the folution, No. 1. and from the 

 green colour which the undiflblved refiduum gave, by fufion, with Cauftic potafh. 



